Steam generator



Feb. 28. 1928.

F. l. DU PONT STEAM GENERATOR Filed Aug. 24. 6,922

3 Shegts-Sheet 1 ATTORMEY 'W/T/VESS:

Feb. 28, 1928.

F. l. DU PONT STEAM GENERATOR Filed Aug. 24. 1922 5 Sheets-Sheet 2 mmwm Hana/Q9 f 0 1: E277 rrafiwfX Feb. 28, 1928. 1,660,437

. F. I. DU PONT STEAM GENERATOR File g- 4, 1922 3 Sheets-Sheet 3 AITOP/VE'K Patented Feb. 28,

uairEn srAr-es 1,660,437 r 'rE r OFFICE.

FRANCIS I. DU PONT, OF WILMINGTON, DELAWARE, ASSIGNCR '10 DELAWARE CHEMI- CAL ENGINEERING COMPANY, OF WILMIIIGTON, DELAWARE, A CORPORATION OF DELAWARE.

i STEAM GENERATOR.

Application-filed August a, 1922. Serial no; 583,956.

This invent-ion relates to an improvement in steamgenerators and more particularly to generators for automobiles. I

steam generator for automobiles is subjected to different requirements than are other steam generators in that sudden and copious drafts are made upon it, and which drafts are generally of short duration.

The steam generator. together with its furnace of a known type of steam driven automobile is not probably over three or tour horse-power, while the engine is capable of delivering about seventy-five horsepower, with steam delivered thereto at the pressure generally carried in generators for steam driven automobiles.

g It will readily be appreciated that as such generators are required to deliver for a short time steam at a rate greatly in excess of the rate at which the steam is generated by transmission of the furnace heat to the water in the boiler, the boiler must afford a reservoir of energy to be drawn upon whenever power greater than the average is needed.

The reservoir ofenergy is afforded by a mass of water heated to about 490 F. and consfequently exerting a steam pressure of 600 lbs.

per square inch. r

When the engine throttle is opened, a

available for use at as rapid a rate as may be needed.

hill at almost any desired speed without the necessity of changing gears. The pressure in the boiler will fall from say 600 lbs. to

the sq. inch to 500 lbs. or perhaps to450 very considerable amount of water spasses over bodily into the cylinders of theengine.-

m This causes a tremendous loss of efiiciency as well as interfering withthe proper mechanical performance of the engine.

The object of my invention is to provide a generator for a steam driven automobile which will deliver dry steam to the engine 0 very considerable amount of energy is A well made steam automobile will on thls account spurt up any ordinary.

regardless of the rate of generation or toam- 'ing caused thereby. 7

Another object of myinvention is to provide a generator of this type which will he stayed in such a manner that it will not tear open over a large area it for any reason a rupture should take place, but confine such rupture to asmall area and thereby avoid an explosion. i My invention provides a steam generator which will havethe safety. features of a water tube boiler, and the reservoir power features of a fire tube boiler. V Y

In fact, the reserve power feature ought to be greater than the usual fire tube boiler as not only is the horizontal area atthe wa ter level greater, but thereis a means of deterring. the foaming which necessarily takes place in any boiler when sudden drafts are made upon it.

Another object of my invention isto provide a boiler which can have anyshape as to horizontal cross-section without lessening its ability to withstand internal pressure. The precise nature of my invention will be best understood by reteren'ceto the drawings, which will now'be described and in which .I haveshown two specific forms, of

my invention, it being premised, however a that changes may be made in the form and construction without departing from the spirit and scope of my invention as defined .in the appended claims.

Fig. :1 is avertical section of one form o generator built in accordance with my invention. V i

Fig. is a detail sectional viewshowing the connections between the-crown-sheet and the water tubes and between the crown-sheet and one of the stay bolts. P

' Figs. 3, 4: and 5 are sectional views through a portion of the generator on the lines 3, 4t and 5 otFig. 1.

Fig. 6 is a detail sectional View showing one form of staying oppositesheets to each other by means of bolts. 3

Fig." 7 is an enlarged sectional View through the joints between side-forming members and the stay sheets. v

Fig. 8 is avertical sectional View through .a modified form of boiler.

The generator shown in Figs. l5 comprises a steam delivery chamber a formed of a cro'wnsheet or bottom plate 6, a top plate; 0, side members 0Z and stay sheets 6,

scribed. Secured to the crown-sheet b and openin into the chamber a are the upper ends of aplurality of rows of vertical. tubes.

and are provided with a reduced body Each row comprises atuhe f and a plurality of shorter tubes 9. The lower ends of all of tubes f are connected to a transverse header 72, while the lower ends of all of the tubes 9 of each row areconnected to a lon gitudinal header :5. One end of each header iis'closed, while the other end thereof is connected to the tube 7 'inthe samerow. The various tubes are preferably welded to the crown-sheet b andto each other at the junction.

The side members are of U-form and the endsof the legs are preferably brazed to the top plate 0, crown-sheet b and stay plates 6.

The members it may be reinforced by means of semi-circular pieces g brazed to the inner surfaces thereof, as shown in Fig. 3.

Extending through the chamber a and secured to thegtop plate 0 and crown-sheet Z) are a plurality ofstay boltsy' which are staggered with relation to the tubes 9 and f. These stay bolts may be of any well known form, and may be secured to the top plate by nuts in and a special safety arrangement to be hereafter described. it In the form shown the bolts are threaded at both ends 301- tion betweenthe threaded ends. i

The crown-sheet may be reinforced at the threaded bolt openings as shown at Z in Fig. 2. i y

The stay sheets e are provided with relatively 'large openings mffor all of the bolts j with the exception of the outer transverse and "longitudinal rowsfas indicated at it. These holes a, Fig. 3, arepreferably of a size to freely permit entrance of the thread ed ends of the bolts and the tap for threading the openings in the crown-sheet.

Surrounding some of the front tubes g of all of the rows are square plates 7),- which together form a baffle plate for directing the flow of gases back and then forth among the tubes as indicated by the arrows in Fig.1-

I have not shown the combustion chamber in connection with the generator, as this may be of any approved type. i

The water line is maintained above the crown-sheet asindicatedin Fig. 1. Water is delivered to header h from which it passes to the lower ends oftubes f and from there to tubes .9 through headers 2'. Steam is drawn from the upper part of chamber a above the upper stay sheet 6. These. stay sheets are preferably formed of heavier sheets than the top plate or side men'ibers in view of the reduction in tensile strength caused by the openings through which the bolts pass. These sheets 6 not. only act as lateral stays forthe sides of the chamber,

butalso form baffles or separators for separating the water from the steam so that rela: tively dry steam is delivered from the steam space of said chamber from between the top plate 0 and the upper stay plate e.-

The exact functioning of these plates in their prevention of foaming over may be described as follows: When the mass of water begins to rise in theboiler on accountyof violent boiling in one place or on account of generation of steam from the whole mass ofwater as when an engine throttle is suddenly opened wide, the mass of bubbles encounters thewater remaining in the lower part and steam in the upper part, before proceeding further upward.

The spaces betweenthe baflie plates (or stay plates), therefore act as aseries of separating chambers and even if the separation is not complete inthe first'space above the water level, there will be more steam and less water in what rises to the next space above. This condition will'always exist so that with asuflicient number of-chamb'ers (which need not be many) a complete separation of water and steam takesplace."

' In Fig. 6 is shown asafety arrangement adapted to release the pressure in the boiler upon the failure of any one of the stay bolts.

Were something of this kind not provided, the failure of one stay "boltywould throw great additional pressure on those immediately around it, andif one of these shonld 'fa-il the pressure would still further on the surrounding bolts.

Finally when there was sufficient unstayed area this would burst out and since the area opened up would be large the bursting would 1 amount to an explosion. This is true of any 'bOllQl or-vessel as ordinarily constructed to resist internal pressureby means of stay bolts.

In Fig. 6, j is the stay bolt. 0 the top plate with its holes larger. than the stay bolts, 3 is a relatively thin sheet of copper extendingover the plate 0 brazed to the top plates 0 along its edges. as at 10 and having holes just large enough for'the stay bolts.

4 is a cap having anexternal and internal.

thread. In assembling the boiler, this cap is screwed down snuglyand brazed only to the copper plate 8 at points 5, but not to anything else.

Thishaving been done, a square washe 7 is put on and held firmly down on the sheet copper 3 by the nut. in, which screws on the external thread of the: cap i.

With the structure described it will be observed that the pressure in the boiler will notblow out the copper. sheet 3 so long as the stay bolt holds, since the copper sheet spanning the area'of the stay bolt hole not occupied by the stay bolt is backed by the cap a threaded on the bolt and which serves to hold the washer 7 against the plate 3 ad jacent the edge of the hole through the engagement therewith of nut- 70; However surrounding bolts.

Another safety feature in this improved boiler is in the side construction and stay plates; This is shown in detail in Fig. 7.

' Here are the stay plates and (Z are the U- plate to the next U-channel beyond.

way, the boiler is much safer than any conshaped channels, which maybe made by slitting a steel tube in half longitudinally. These are preferably brazed at points 9 to the plates and in the manner shown. The rea son I prefer brazing to welding here is that the stay plates themselves are not melted or in any way changed by the operation. Now if the internal pressure should become too great, one of the U-channelsorhalf tubes d4 would burst out in one place just as one of the tubes in a water tube boiler bursts under similar stress. There is, however, no coneeivable way in which-a burst or tear in the U-channels (5. could extend across the stay In this struction in which a larger external shell withstands the pressure, for in this case when the internal pressure is too great for the shell a tear undoubtedly starts in one place, but the shell being uniform it proceeds instantly along or around the shell and opens up a large area out of which the contents of the boiler escape with explosive violence.

In Fig. 8 I have shown a boiler without 'ater tubes and in which the oppositeend plates or :top and bottomplates cand b" are connected to each other by means of fire tubes 3'' which also act'as stay-bolts orrods. In this form, there are no water tubes, the

water being heated by the hot gases which pass through the tubes 7". These tubes 7' are welded to sheets 5 and c and pass through openlngs m in stay sheets 6. These stay sheets 0 are connectedat their edges to sideforming members d above described.

The advantages of any invention result from the provision of a steam generator in which the side wall stays connect all the side as in the structure walls to each other throughout the length'of the side walls and which stays are spaced from each other to form a chamber having a plurality of interconnected compartments,

whereby the steam is separated from the water. Also from the provision of such side wall stays which will permit for ming sectional' side walls the different members of which are separated by the stays, the va rious stays being so arranged thatthe wallforiningportions of the chamber donot form a continuousvsheet through which a rupture if started could be propagated. Also from the provision of a generator in which the end walls are stayed by means of stays which extendthrough openings in the side wall stays. Further, from the provision of a steam generator having a plurality. of tubes communicating at one end with a common chamber having stays connecting the upper and lower walls to each other, as well as stays connecting opposite side walls to each other. Further, from the provision of a generator which can be made'of any desired shape without interfering with the strength factor. e

Having now fully described my invention, what I claim and desire to prote'ctby'Let-ters Patent is: I a

1. A steam generator having-end sheets," a plurality of side-forming members for forming each side, transverse stay meinbcrs, the side-forn'iing members of each side being secured to the transverse stay members independently of each other, and stay members connected to the end sheets, therebeing openings through the transverse stays through which the end sheet stay members extend. r

l 2. A steam generator having end sheets, a plurality of side-forming members for forming each side, stay sheets substantially parallel with the end sheets, the side-forming members on each side being connected to said stay sheets independently, said "stay sheets acting as stays for the side-forming sheets extending from sideto side both laterally and transversely between the legs of the channel members and connected thereto independently,and stay rods connected to the end sheets and extending through openings in the stay sheets. I

4. A steam generator comprising a plurality of substantially vertical wat'ertubes connected to each other for circulation at their lower ends and connected directly at their upper ends to a steam and water drum, the drum having side and end walls, stays connecting the end walls to each other at a plurality of points over their entire area, and a'plurality of perforated stay sheets connecting the side walls to each otherat a plurality of points over their length and height. v

llu

I 5. A steam generator comprising a plurality of water tubes connected to each other for circulation at one end and connected directly at the other end to a steam and water drum, the drum having upper and.

lower walls, spaced stay bolts connecting the upper and lower walls to each other, and spaced stay plates connected to all of the side walls, said stay plates having openings through which the stay bolts extend.

6. A steam generator comprising a plurality of substantially vertical water tubes connected to each other for circulation at their lower ends and connected directly at their upperends to a steam and water drum of rectangular form, the drum having upper and lower walls, spaced stay bolts connecting the upper and lowerwalls to each other, and spaced stay plates connected to all of the side walls said stay plateshaving openings through which the stay bolts extend.

7. A steam and water drum for a steam generator having top and bottom plates, the bottom plate being arranged to be connected W to the upper ends of water tubes, regularly spaced stay bolts connecting the top and bottomplates to each other, the side walls being each formed of a plurality of mem bers, and tie plates parallel with the top and bottom plates, said tie plates being secured between ad acent side wall-tormmg members, sa d tie plates havnig openings therethrough through which the tie rods extend.

8. A steam generator having substantially vertical water tubes connected to each other at their'lower ends by headers, a steam and water'drum connected to the upper ends of said tubes, said steam and water drum being formed of a plurality of channel-shaped side members in different horizontal planes,

a bottom plate connected to the lower flanges of the lowermost side-forming members, said bottom plate being connected to the upper ends of the tubes, a top plate connected to the upper flanges of the uppermost sideforming member, a tie plate interposed be tween adjacent" side-forming members and connected to the upper flange of one member and the lower flange ot the upper member, and stay bolts connected to the upper and through both perforations, means preventing steam from leaking out between the stay bolt opening in the plate and the bolt, and other means associated with the bolt for holding the plate in position on the top sheet. p

.10. A steam and water drum for a steam generatorhaving top and bottom plates the top plate being perforated for the passage of a stay bolt, a plate of relatively light material perforated for the reception of an cnd'of a stay bolt, superimposed onsaid top plate, means for securing said stay bolt to said superimposed plate and means for se-' curing said superimposed plate to said top,

plate through the medium of said stay bolt. 11. A steam and water drum for a steam generator having top and bottom plates, the

top plate being perforated for the passage of a stay, bolt, a perforated plate superim-- posed on said top plate, a stay bolt, acap' engaging the end of the stay bolt and secured to said superimposed plate andimeans engaging the sald cap adapted to secure said superimposed plate to said top plate, through the medium of said staybolt. V a

12. Asteam generator having an end sheet stayed to another portion of the generator by a stay bolt, said sheet having an opening therethrough through which the stayIbolt passes, a superimposed plate on the end sheet surroundingthe bolt and secured to the end sheet at a distance, from the stay bolt to. prevent leaking, and stay boltsecuring means secured to the bolt and adapted to hold the plate-incontact with the sheet.

13. A, steam generator having an end sheet stayed by means of a plurality of stay bolts extending from another portion of the generator through openings through the sheet said openings being of substantially greater diameters than the diameters of the.

bolt, a relatively thin plate superimposed on the end sheet and secured at its edges to the end sheet, said sheet having openings through which the bolts extend, a threaded head on each bolt secured to the superimposed sheet, awasher surrounding each bolt head and engaging the superimposed sheet,

and a nut on each head for drawing the washers into holding position on the plate.

14;. A steam and waterdrum fora steam generator comprising top and bottom and side plates, a plurality of rigid continuous sheets extending transversely of the drum and connected to all sides thereof, and stay bolts extending between the top and bottom plates, said sheets being'provided with per forations of greater diameter than thatoi the stay bolts through which the stay bolts pass in their extension.

In testimony of which invention, I have hereunto setmy hand, at Philada, Penna, on this 9th day of August, 1922.

FRANCIS I. nu PONT. 

